If you search for the millennial makeup brand Glossier on YouTube, one of the first results likely to appear is from Olivia Jade, a fashion and beauty vlogger with over one million subscribers. Her 2017 video "First Impression & Review of Glossier Makeup" has garnered over 630,000 views. In the video's description, Jade writes "this video is not sponsored!" She fails to mention, though, that a list of products featured in the video include a series of affiliate links produced by RewardStyle, an agency that creates affiliate marketing campaigns for influencers like Jade. If a viewer clicks on a RewardStyle link and buys a product like Glossier's Hydrating Moisturizer or Boy Brow Gel, Jade likely gets a cut of the sale.

Jade is far from the only influencer to neglect to disclose affiliate marketing relationships according to Federal Trade Commission guidelines. New research released from Princeton University Monday indicates that the vast majority of similar marketing set-ups go undisclosed by influencers on platforms like YouTube and Pinterest.

In a paper to be presented at the 2018 IEEE Workshop on Technology and Consumer Protection in May, Princeton's Arunesh Mathur, Arvind Narayanan, and Marshini Chetty analyzed a representative sample of over 500,000 YouTube videos and over 2.1 million unique Pinterest pins collected from August to September 2017. Of those, 3,472 videos and 18,237 pins had affiliate links. And of that subset, researchers found that only 10 percent of YouTube videos and seven percent of Pinterest pins contained any written disclosure.

The majority of YouTube and Pinterest influencers are likely making a profit off their product reviews—even without direct corporate sponsorship—without disclosing that fact to users.

The vast majority of disclosures that the Princeton researchers did find don't even abide by FTC guidelines. In 2013, the agency began requiring that affiliate links embedded within product reviews include a disclosure. In the current version of the guidelines, bloggers are required to include more than just the phrase “affiliate link,” because readers and viewers may not know what the term means. The FTC instead recommends that bloggers use a short explanatory phrase, like “I make a commission through purchases made through this link.”

Of the few disclosures the researchers found, most merely included phrases like "affiliate links may be present above." Disclosures that contained an actual explanation of what an affiliate link is only accounted for a tiny fraction of the YouTube videos and Pinterest pins the researchers looked at. That means the majority of YouTube and Pinterest influencers are likely making a profit off their product reviews—even without direct corporate sponsorship—without disclosing that fact to users. (Like most online publications, WIRED also participates in affiliate marketing).

"​Disclosures are important so users can give—in their minds—appropriate weightage to content creators’ endorsements," says Arunesh Mathur, a computer science graduate student at Princeton and the lead author of the paper. He says that his study's findings likely don't represent all undisclosed affiliate marketing campaigns on Pinterest and YouTube, because the researchers didn't take into consideration other forms that don't include links, like coupon codes.

The study also only included descriptions written in English, and couldn't account for other kinds of undisclosed marketing relationships, like when an influencer is given a product for free, or paid a fee behind the scenes to promote it. In fairness, the research also doesn't take into account instances in which a vlogger discloses the affiliate marketing campaign in the video itself, or within the image on Pinterest. Mathur, though, doesn't believe most disclosures take that form. "We're fairly confident that only a tiny fraction of content creators disclose affiliate links at places other than the description," he says.

The Princeton research underscores how murky the world of product reviews on YouTube and Pinterest really is, where it's often impossible to definitively know how an influencer profits from a post. And since affiliate links tend to be used by more popular accounts, recommendations and search engines are more likely to surface posts that have them.

To be clear, there's nothing inherently wrong with affiliate marketing, and the inclusion of an affiliate link doesn't automatically mean that a review is biased. But if consumers don't know that a blogger profits when they make a purchase, there's no chance to gauge whether that incentive may have colored an influencer's perspective. Affiliate marketing is also only one facet of the largely unregulated online review space. Many bloggers fail to tell their readers when everything from lip gloss to entire vacations have been paid for.

In August of last year, the FTC sent over 90 letters to celebrities and influencers reminding them that they should clearly disclose brand relationships. But the agency itself sometimes can't even distinguish between an advertisement and a normal post—underscoring how muddled the two have become. The FTC did not immediately return a request for comment.

'Web browsers can arguably do more in alerting users about sponsored content.'

Arunesh Mathur, Princeton University

Young influencers suddenly flush with social media followers may also not be aware of the FTC's guidelines or how exactly they are required to disclose partner relationships. "I think a lot of bloggers are still navigating the ins and outs of disclosures. For example, maybe they're unsure if there's a different way to disclose a paid promotion compared to a gifted product or service," says Austen Tosone, a fashion blogger with an Instagram and YouTube presence. "I definitely think that my readers want to know whether or not something I post is sponsored. Even if it's a brand I use and love a lot, if I'm being paid to create content for them or was sent a product with the agreement that I'd review it on one of my social channels, I always still disclose that relationship."

Full-time influencers, whose followers can number in the millions, are also often represented by talent agencies who help broker deals between them and brands. The agency is partially responsible for ensuring that the blogger properly discloses posts paid for by corporations. "Each contract we have with our influencers requests that they disclose paid sponsorships on their posts and blog articles," a representative for the influencer agency WTS Connect said in an email.

Social platforms have also begun to fight back against undisclosed marketing by incorporating features that allow influencers to add prominent disclosures automatically. Instagram, for example, began testing a feature last year that adds a disclosure at the top of a post saying it's sponsored by a specific brand. YouTube also lets vloggers add an overlay to their videos that reads "Includes paid promotion." Facebook too introduced a feature in 2016 that allows influencers to label when a post is paid for by a specific business.

Participating in an affiliated marketing campaign doesn't necessarily mean an influencer's review is sponsored per se. They may have paid for the products themselves, but then merely receive a commission if someone else buys them too. "These [features] are tailored towards product placements and paid partnerships, and a content creator who engages in affiliate marketing strictly might be less inclined to embrace these disclosures," says Mathur.

The most practical solution may end up being browser-based. Mathur and his co-authors plan next to build an extension that can detect and highlight affiliate marketing campaigns automatically, so consumers can be aware immediately of any financial incentive in the review they're watching. "Web browsers can arguably do more in alerting users about sponsored content since many of the accompanying disclosures can be detected—where present—using machine learning and natural language processing techniques," says Mathur.

For now, make sure to scan the links below a blogger's video before taking their word about Glossier's latest.

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